Transport device for blanks, especially for machine tools



1967 K. DANGFILMAIER ETAL 3,353,822

ESPECIALLY FOR MACHINE TOOLS TRANSPORT DEVICE FOR BLANKS,

Filed Dec.

United States Patent Ofiice 33 12%? 3,353,822 TRANSPGRT DEVKIE FOR BLANKS, ESPECIALLY FOR MACHINE TOULS Karl Dangelmaier, Eislingen (Fils), Karl Griesinger, Goppingen-Jebenhausen, Otto Kurz, Hattenhofen, and Franz Schneider and Herbert Scholl, Goppingen, Germany, assignors to Messrs. L. Schuler A.G., Goppingen, Germany Filed Dec. 22, 1965, Ser. No. 515,546 Claims priority, application Germany, Jan. 5, 1965,

' Sch 36,336

8 Claims. (Cl. 27118) This invention relates to a device for transporting blanks of ferromagnetic material vertically of their plane along a path. More specifically this invention relates to a device for feeding blanks from the top of a stack to a machine tool, the stack being provided with magnets. In known devices of this type the magnets are arranged only at the upper end of the stack and serve for spreading the blanks, i.e. they are intended to prevent two blanks from sticking together at their edges due to the presence of burr thereon and being taken together from the stack and fed to the machine tool. The spreading effect is due to the fact that two ferromagnetic bodies in a magnetic field will repel each other. In known devices the spreading magnets were so designed as to form a field as homogeneous as possible in the end region of the stack.

In these known devices the entire stack of blanks had to be advanced with the aid of a lifting device engaging the lowermost blank at the same rate as the blanks were removed at the top by a gripping or like device and fed into the machine tool.

It is the object of the present invention to provide a transport device of the above-described type in which such a lifting device is not required.

The invention consists in that pairs of poles of magnets are arranged along the transport path of the blanks in planes extending vertically of the transport direction and at least one pair of poles is adapted to be switched on and off for the purpose of shifting' planes having a concentration of magnetic flux lines.

A particular advantage of the device designed as proposed by the invention resides in that it permits blanks to be lifted from the top of a stack and to be moved individually into a plane from where they can be fed into the machine tool with the aid of a gripping or like device. In the known transport devices a special device for lifting the stack is required which always lifts the stack to a height in which the uppermost blank of the stack is in the plane for being taken over by the gripping device. This special lifting device is avoided in the arrangement proposed by the inventionpThe transport device according to the invention also ensures that always only one single blank will be moved into the plane where it is taken over by the gripping device. It is very difiicult to achieve this with mechanical transport devices bridging the ever increasing distance between the upper end of the stack and the plane in which the blank is received by the gripping device.

In one embodiment of the invention the pairs of poles are adapted to be switched on and off independently of each other. This embodiment permits the individual blanks to be moved especially rapidly. The pairs of poles may be provided in staggered arrangement along the transport path, e.g. they may be relatively displaced in helical, rectangular or other lines. When several pairs of poles are arranged in one plane the two pole faces of a magnet may be arranged adjacent each other and extend at an angle relative to each other in one embodiment of the invention. When these two pole faces, according to a further development of this embodiment, have the form of polygonal courses, it is possible to use always the same pole faces irrespective of the diameter of the transported blanks.

In one embodiment of the invention at least the poles of the pair arranged at the end of the transport path have a sharp edge defining in a manner known per se the plane of greatest concentration of magnetic flux lines. This is the plane in which the blanks are taken over by a following transport means. Each blank has a permanent tendency of entering into the plane between poles where in the absence of blanks the greatest density of magnetic flux lines occurs.

In a further embodiment of the invention the individual pole pairs arranged along the transport path may be connected with each other by a thin ferromagnetic metal sheet.

When processing blanks having a recess in which a bolt engages at least over a partial section of the transport path, also the bolt may have magnetic poles according to a further embodiment of the invention.

Several embodiments of the invention will now be described by way of example and with reference to the accompanying drawing, in which:

FIG. 1 is a schematic section through an embodiment of the transport device according to the invention with magnets switched off;

FIG. 2 is a similar view of the same arrangement with magnets switched on;

FIG. 3 is a lateral View showing an embodiment of the pole faces of a magnet; and

FIG. 4 is a similar view of another embodiment of the pole faces of a magnet.

In the embodiment of the invention shown in FIG. 1 the poles 10 and 11 of a solenoid or a strong controllable permanent magnet are arranged on either side of a transport channel 1 which may be closed at its lower end by a ferromagnetic plate 2, the poles 10 and 11 being disposed at the end adjacent this plate 2. A pair of poles 6 and 7 of another magnet is provided at a distance 5 the length of which is dependent on the power of the magnets used and produces an inhomogeneous field of force heavily concentrated in the plane schematically indicated by the points.

Further pairs of poles 14 and 15, 16 and 17, and 18 and 19 are arranged at further distances apart.

In FIG. 1 the magnets are switched off. A stack 8 of individual blanks 9 rests on the plate 2 adjacent the magnetic poles 10 and 11 which are so designed as to produce a magnetic field substantially homogeneous in the range of the transport path along which they are arranged.

FIG. 2 shows the position of the blanks when the magnets are switched on. The magnet with the poles 10 and 11 works as a spreading magnet. The blanks 9 exert repulsive forces on each other and are driven apart. As a result the uppermost blank 9' moves into the range of the highly inhomogeneous magnetic field produced by the magnetic poles 6 and 7 and is pulled thereby into the plane of greatest concentration of magnetic fiux lines. The second blank 9" can however not follow this movement as long as it is still under the repulsive force of the blank 9'. The blank 9' is initially retained in the plane defined by the points of the pole shoes 6 and 7. As soon as the blank 9' is removed from the region between the pole shoes 6 and 7 the dispersion of the magnetic field produced by the pole shoes increases again substantially and this field then exerts a greater attractive force on blank 9 that has been repulsed from the stack so that blank 9 after the repulsive forces of blank 9' have also disappeared, will immediately jump into the plane of greatest flux density of the magnetic field produced by the pole shoes 6 and 7 and another blank of the stack will move up into the position previously occupied by blank 9".

In the plane defined by the sharpedges of the pair of poles 18 and 19 a transport means, for example a gripping device, grips the blank located there and feeds it into a machine tool, for example a press. For moving blank 9' from the plane defined by the pair of poles 6 and 7 into the plane of the pair of poles 18 and 19 the device proposed by the invention includes means for shifting at least one plane of greatest magnetic flux density in the direction of movement of the blanks without mechanical intervention. The travelling magnetic field thus assumes the function of a lifting device which carries the blanks individually into their final position between the poles 18 and 19. To permit this shifting of a plane of greatest magnetic flux density, at least one pair of poles is arranged to be switched on and off.

This switching on and oif can be achieved by cutting in and out the exciting windings of the solenoids or by short-circuiting the magnetic flux of the magnets. Thus when, as shown in FIG. 2, the magnet with the pole shoes 14 and 15, i.e. the one adjacent to the magnet with the pole shoes 6 and 7, is switched on, there is again an inhomogeneous magnetic field between the pole shoes 14 and 15. This field exerts an attractive force on the blank located between the pole shoes 6 and 7 since there is as yet no blank between the pole shoes 14 and 15.

Therefore, when the magnet with the pole shoes 6 and 7 is switched off the blank previously located between these pole shoes will jump into the plane of greatest magnetic flux density between the pole shoes 14 and 15. When the magnet with the pole shoes 6 and 7 is switched on again the uppermost blank of the stack will again jump into the plane of greatest magnetic flux density of the magnetic field produced by the pole shoes 6 and 7. When now the following magnet is switched on, the pole shoes 16 and 17 of which again produce an inhomogeneous field, and when after that the magnet with the pole shoes 14 and 15 is switched off, the blank previously located between the pole shoes 14 and 15 will jump into the plane of greatest magnetic flux density between the pole shoes 16 and 17. When then the field between the pole shoes 14 and. 15 is built up again and the field between the pole shoes 6 and 7 is switched off the field between the poles 14 and 15 draws up again a blank from below, i.e. from the position between the pole shoes 6 and 7, for the blank located between the pole shoes 16 and 17 cannot be retracted into the field between the pole shoes 14 and 15 since this blank is retained by the field between the pole shoes 16 and 17. For the same reason the uppermost separated blank of the stack will jump up after the magnet with the pole shoes 6 and 7 has been switched on again. When thereupon a magnetic field is produced between the pair of poles 18 and 19 and the magnetic field between the pair of poles 16 and 17 is switched off the blank located in the plane of the last-mentioned pole shoes will jump up into the plane of the pole shoes 18 and 19. After this the field between the pair of poles 16 and 17 is switched on again and the field between the pair of poles 14 and 15 is switched off, after which the following blank moves up into the plane of the pair of pole shoes located at a higher level and so on. When the blank between the pair of poles 18 and 19 is removed at the end of the transport path it is only necessary in the illustrated embodiment to switch off the field of the subjacent pair of poles to cause a blank to jump up into the final position and the cycle is repeated as has been described above.

It is not necessary that the magnet located adjacent the stack is designed as a spreading magnet with a magnetic field as homogeneous as possible. Rather, the pole shoes of this magnet may be so designed that its field is also inhomogeneous and has its greatest magnetic flux density in a plane that may, for example, be located near the upper edge of the stack. It is only necessary to ensure that there are always at least two blanks in the range of this magnetic field that exert repulsive forces on each other so that the uppermost blank will be urged upwardly out of the range of greatest magnetic flux density and this blank can jump into the field between the following pole 4 shoes 6 and 7 when no blank is present in the range of this field.

In various embodiments of the invention it is, of course, possible to provide for the field of the uppermost pair of poles 18 and 19 to be switched off independently of whether there is a transport movement or not, when the following transport device, e.g. a gripping or like device, grips the blank and moves it on.

The device proposed by the invention may be so designed that the stack of blanks 8 can be introduced from above, from the side or from the bottom after removing the plate 2.

In the drawing all the poles are shown as being located in the drawing plane. It is, of course, possible, in various embodiments of the invention, to displace the pairs of poles around the axis of the direction of transportation. This is especially advisable when the optimum distance between the planes of greatest magnetic flux density is so small that the exciting windings of the electromagnets cannot be accommodated if all the magnets are arranged in alignment one above the other. The magnets may be arranged, for example, in crosswise or helical displacement relative to each other around the transport path.

It is not absolutely necessary to separate the transport path by a non-ferromagnetic housing from the pole shoes producing the magnetic fields. Such a channel wall may also include magnetically conductive metal sheets 26 and 27 interconnecting the individual poles arranged one behind the other in the direction of transportation. This arrangement will give the path sections between the individual pairs of poles a somewhat greater field strength.

Blanks having a central recess are generally guided by a bolt engaging in a recess of the blank. In one embodiment of the invention this bolt is provided with magnetic poles arranged in the plane of the other magnetic poles at the edge of the blank. If it is a case of large blanks, so that the distance between the individual poles engaging the edge of the blank is relatively great, this arrangement proposed by the invention of providing pairs of poles also on the bolt substantially increases the forces helping to move the blanks and thereby also the disadvantage is avoided that large blanks will sag in the center when the magnets only act upon their edges.

The invention is not restricted to the provision of only one pair of poles in each plane. Rather, any desired number of pole pairs may be arranged in any one plane. When several pole pairs are arranged in one plane the pole faces 20 and 21 of a magnet may be designed, as shown in FIGS. 3 and 4, so as to extend at an angle relative to each other. In this case the magnet has a yoke 22 carrying the exciting winding 23. This form is especially suitable for circular blanks. In the embodiment shown in FIG. 4 the pole faces 24 and 25 have the form of polygonal courses. This form is especially suitable where it is desired that the diameter of the transport channel should be adapted to be varied in accordance with the varying diameters of the transported blanks. In this case the magnets may also be arranged in the device for adjustment radially of the axis of the transport channel.

We claim:

1. A device for transporting individual blanks of ferromagnetic material vertically of their plane along a path, especially a device for feeding blanks from the top of a stack to a machine tool, the stack being provided with spreading magnets, characterized in that pairs of poles are arranged along the transport path of the blanks in planes extending vertically of the transport direction and at least one pair of poles is adapted to be switched on and off for the purpose of shifting planes having a concentration of magnetic flux lines.

2. A device as claimed in claim 1, characterized in that the pairs of poles are adapted to be switched on and off independently of each other.

3. A device as claimed in claim 1, characterized in that the individual pairs of poles arranged along the transport path and having the same polarity are interconnected by a thin ferromagnetic metal sheet.

4. A device as claimed in claim 1, characterized in that at least the poles of the pair arranged at the end of the transport path are provided with a sharp edge defining in a manner known per se the plane of greatest concentration of magnetic flux lines in which the blank is taken over by the next following transport means.

5. A device as claimed in claim 1, characterized in that the pairs of poles are displaced relative to each other along the transport path.

6. A device as claimed in claim 1, for transporting blanks having a recess in which a bolt engages at least over a partial section of the transport path, characterized in that the bolt is provided with magnetic poles.

7. A device as claimed in claim 1, characterized in that a plurality of pole pairs are arranged in one plane, the two pole faces of each magnet being arranged adjacent each other and extending at an angle relative to each other.

8. A device as claimed in claim 7, characterized in that the two pole faces have the form of polygonal courses.

References Cited UNITED STATES PATENTS 2,795,340 6/1957 Hommel 2148.S X 2,860,874 11/1958 Gulick 27118.1 X

HUGO O. SCHULZ, Primary Examiner.

G. F. ABRAHAM, Assistant Examiner. 

1. A DEVICE FOR TRANSPORTING INDIVIDUAL BLANKS FOR FERROMAGNETIC MATERIAL VERTICALLY OF THEIR PLANE ALONG A PATH, ESPECIALLY A DEVICE FOR FEEDING BLANKS FROM THE TOP OF A STACK TO A MACHINE TOOL, THE STACK BEING PROVIDED WITH SPREADING MAGNETS, CHARACTERIZED IN THAT PAIRS OF POLES ARE ARRANGED ALONG THE TRANSPORT PATH OF THE BLANKS IN PLANES EXTENDING VERTICALLY OF THE TRANSPORT DIRECTION AND 